1. Field of the Invention
The present invention relates to an information input device and a display device, and more particularly, to an information input device and a display device which include a panel which is provided with an electrostatic capacitance touch sensor for sensing a close position of a sensing target body.
2. Description of the Related Art
A display device such as a liquid crystal display device or an organic EL device has advantages of a thin and lightweight configuration and low power consumption. Thus, the display device is widely used in mobile electronic devices such as cellular phones or digital cameras.
In such a display device, the liquid crystal display device is provided with a liquid crystal display panel in which a liquid crystal layer is inserted between a pair of substrates, as a display panel. For example, the liquid crystal display panel is a transmission type. Here, the liquid crystal display panel modulates and transmits illuminating light emitted from a backlight which is installed on a rear surface of the liquid crystal display panel. Then, display of images is performed on a front surface of the liquid crystal display panel by the modulated illuminating light.
The liquid crystal display device is, for example, an active matrix type. Here, the liquid crystal display device includes a TFT array substrate which is formed with a plurality of thin film transistors (TFTs) which serves as pixel switching elements. In the liquid crystal display panel, an opposite substrate is arranged to be opposite to the TFT array substrate, and the liquid crystal layer is disposed between the TFT array substrate and the opposite substrate. In this liquid crystal display panel of the active matrix type, as the pixel switching elements input an electric potential to pixel electrodes, voltage is applied to the liquid crystal layer, and the image display is performed by controlling the transmittance of the light which passes through the pixels.
In the above described display device, a touch panel may be provided on the display panel as an information input device so that a user can input manipulation data using images such as icons which are displayed on a screen of the display panel.
In this respect, the touch panel may be externally provided on the display panel, or the function of the touch panel may be installed in the display panel.
For example, there has been proposed a display panel in which an electrostatic capacitance touch sensor is installed (for example, refer to Japanese Unexamined Patent Application Nos. 2008-9750, 2009-3916 and 2008-129708).
Here, the electrostatic capacitance touch sensor is configured so that capacitance can be varied when a sensing target body is close to a sensing surface. A position in which the sensing target body is close to the sensing surface is detected on the basis of the variation of the capacitance.